Androgen deprivation therapy for prostate cancer: prescribing behaviors and preferences among urologists

Introduction — Several androgen deprivation therapy (ADT) medications are available for treating advanced prostate cancer with roughly equivalent oncological efficacy and tolerability. We investigated the proportion of physicians who predominantly prescribe one type of ADT drug ("mono-prescriber") and assessed characteristics associated with prescription behavior.

Methods — Ontario men aged ≥65 years who were diagnosed with advanced prostate cancer (1997-2017) and initiated ADT thereafter for ≥3 consecutive months were identified using population-level administrative data. Their first prescription for injectable ADT was linked to a physician, and urologists with ≥10 prescriptions over the study period were included in the analysis (n=282). Urologists were classified as high mono-prescribers if ≥80% of their prescriptions were for one drug type. Multivariable logistic regression was used to examine the association of physician characteristics with the odds of being a high mono-prescriber.

Results — Overall, 67 (23.8%) of urologists were classified as high mono-prescribers but the frequency varied across health planning regions. The most commonly prescribed drugs and those used by mono-prescribers were goserelin (41.8% and 56.7%) and leuprolide (44.3% and 43.3%), respectively. In multivariable analysis, the odds of a physician being a high mono-prescriber were higher with more years in practice (odds ratio [OR] 1.06/year, 95% confidence interval [CI] 1.03-1.09, p<0.0001) and lower for higher patient volume (OR 0.33 for above vs. below median, 95% CI 0.17-0.63, p=0.0008).

Conclusions — Overall, one in four urologists were classified as high mono-prescribers. Mono-prescribers had more years in practice and smaller volume practices, potentially suggesting habitual prescription behavior and/or the effect of external pressures.